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Small u(kappa) at singular kappa with compactness at kappa++

2019/10/31 by Honzik, Radek, Stejskalova, Sarka
#FOS: Mathematics #Logic (math.LO)

paper · doi:10.48550/arxiv.1910.14391

Abstract

We show that the tree property, stationary reflection and the failure of approachability at κ++ are consistent with \mathfraku(κ) = κ+ < 2κ, where κ is a singular strong limit cardinal with the countable or uncountable cofinality. As a by-product, we show that if λ is a regular cardinal, then stationary reflection at λ+ is indestructible under all λ-cc forcings (out of general interest, we also state a related result for the preservation of club stationary reflection).

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